Play Glacial Chasm either from your hand or from your graveyard.
When Glacial Chasm enters the battlefield, its second ability triggers, causing you to sacrifice another land you control.
Play any land from your graveyard.
At the beginning of your next upkeep, Glacial Chasm's cumulative upkeep ability triggers, allowing you to choose not to pay the cost and sacrifice it instead.
Repeat.

Prevent all damage that would be dealt to you

Lock

Glacial Chasm

Ramunap Excavator

Druid Class

Animate a Forest that enters untapped using Druid Class
Cast Springheart Nantuko for its bestow cost by paying {1}{G}, attaching it to the animated Forest.
Play a land. When the land enters, Springheart Nantuko triggers, causing you to pay {1}{G} to create two token copies of the Forest that enters untapped.
When the Forest tokens enter, Springheart Nantuko triggers twice.
Holding priority, activate the Forest tokens by tapping them, adding {G}{G}.
Resolve the first Springheart Nantuko trigger, choosing not to pay and creating two 1/1 Insect creature tokens.
Resolve the second Springheart Nantuko trigger, causing you to pay {1}{G} to create two token copies of the Forest that enters untapped.
Repeat from step 4.

Infinite creature ETB

Infinite creature tokens

Infinite landfall triggers

Infinite tapped Forest tokens

Springheart Nantuko

Doubling Season

Animate the land that has Squirrel Nest attached using Druid Class.
Activate the land with Squirrel Nest attached by tapping it, creating a 1/1 Squirrel creature token.
When the Squirrel enters, Intruder Alarm triggers, untapping all creatures.
Repeat from step 2.

Infinite mana creatures you control can produce

Infinite untap of creatures

Squirrel Nest

Intruder Alarm

Activate Druid Class's third ability by paying {4}{G}, causing it to become level three.
Druid Class's third ability triggers, causing Minamo to become a */* creature with haste that's still a land.
Activate Arixmethes by tapping it, adding {G}{U}.
Activate Minamo's second ability by paying {U} and tapping it, untapping Ioreth of the Healing House.
Activate Ioreth of the Healing House's second ability by tapping it, untapping Minamo and Arixmethes.
Repeat from step 3.

Infinite green mana

Ioreth of the Healing House

Arixmethes, Slumbering Isle

Minamo, School at Water's Edge

Activate Druid Class's third class ability by paying {4}{G}, causing it to become level 3 and causing Grove of the Burnwillows to become a creature.
Activate Marvin using Grove of the Burnwillows' second ability by tapping it, adding {R} or {G} and causing each opponent to lose 1 life due to Tainted Remedy.
Activate Marvin using Pili-Pala's ability by paying {2} and untapping it, adding {1}.
Repeat from step 2.

Infinite lifeloss

Grove of the Burnwillows

Pili-Pala

Marvin, Murderous Mimic

Tainted Remedy

Activate Druid Class's third ability by paying {4}{G}, causing it to become level 3, and causing the land with Tarmogoyf Nest attached to become a creature.
Activate any number of creatures you control by tapping them, adding at least {1}{G}.
Activate the land with Tarmogoyf Nest attached by paying {1}{G} and tapping it, creating a Tarmogoyf creature token.
When the Tarmogoyf enters the battlefield, Intruder Alarm triggers, untapping all creatures.
Repeat from step 2.

Tarmogoyf Nest

Combos with "Druid Class"